Various analytical instruments can be used for analyzing analytes, such as proteins and other biomolecules. Mass spectrometry systems have gained prominence because of their ability to handle a wide variety of analytes with high sensitivity and rapid throughput. For example, biomolecules can be identified via analysis of spectra acquired using a mass spectrometry system. In some instances, a mass spectrometry system may be coupled to a chromatography system to identify analytes present in a sample stream. Typically, the sample stream passes through a chromatography column, such as a High Performance Liquid Chromatography (“HPLC”) column, which is packed with a stationary phase that has adsorbent characteristics. The analytes can exhibit different levels of adsorption onto the stationary phase, thus allowing the analytes to be separated as they exit the chromatography column. Successive eluting portions of the sample stream flow from the chromatography column into the mass spectrometry system, which repeatedly scans the sample stream to acquire spectra from the eluting portions. Typically, the spectra are then processed for presentation in a manner that facilitates identification of the analytes as chromatographic peaks. Such processing is sometimes referred to as “chromatogram reconstruction” and can be used to derive a variety of chromatograms, such as total ion chromatograms, base peak chromatograms, and mass chromatograms. Detection and characterization of a peak in a resulting chromatogram allow for identification of an analyte associated with the peak as well as determination of an amount of that analyte in the sample stream.
Certain conventional techniques for detection and characterization of peaks rely on taking first or second derivatives of a chromatogram to determine whether and where a peak is present. Such conventional techniques can perform in a satisfactory manner for processing smooth, Gaussian-like peaks in a relatively noise-free environment. However, certain types of mass spectrometry systems present challenges in terms of accuracy and efficiency at which resulting chromatograms can be processed. One particular type of mass spectrometry system that is often used is a tandem mass spectrometer, such as a tandem quadrupole mass spectrometer. A tandem quadrupole mass spectrometer is also sometimes referred to as a “triple quadrupole mass spectrometer.” Chromatograms derived using a tandem quadrupole mass spectrometer can sometimes comprise jagged peaks and a relatively high level of noise, which can sometimes occur as spikes. Such characteristics of the chromatograms can cause conventional techniques to perform poorly. In particular, conventional techniques can erroneously characterize a single, jagged peak as multiple peaks and can erroneously detect spikes or other types of noise as peaks. In addition, conventional techniques can be prone to errors with respect to start and stop points when calculating an area of a peak.
These deficiencies of conventional techniques result from taking derivatives, since taking a derivative of a signal generally enhances a level of noise in that signal. Attempts have been made to address these deficiencies using adjustable parameters that control a degree of smoothing. However, such attempts can require supervision by an experienced user, who manually selects or tunes the adjustable parameters. As can be appreciated, manual selection of the adjustable parameters can be tedious and time-consuming. Moreover, the adjustable parameters may have to be repeatedly re-tuned over the course of different measurements, thus complicating a subsequent measurement workflow as well as subjecting the subsequent measurement workflow to bias, errors, or inconsistencies.